The present invention relates to a new and improved construction of apparatus for engaging and moving individual flat structures, especially paper sheets or printed products or the like.
The apparatus of the invention is of the type comprising at least one suction head which can be movably applied, by means of a drive device, at a respective flat structure for engagement therewith, the suction head entraining the engaged flat structure until it is released. Further, there is provided a valve arrangement, controlled by the drive device and connected with a negative pressure source at the suction head. The valve arrangement periodically connects or flow communicates the suction head with the negative pressure source in order to engage one of the flat structures. With such type equipment, as for instance is known from the German Patent Publication No. 27 32 591, the valve arrangement must periodically connect the suction head, moved along a closed path of travel, with the negative pressure source for a certain amount of time, so that the suction head can engage and entrain the flat structure which is to be moved. In order to be able to again release the engaged flat structure, the suction head again must be disconnected by the valve arrangement from the negative pressure source and vented. During each operating cycle of the suction head it is therefore necessary for the valve arrangement to firstly connect the suction head with the negative pressure source, thereafter to disconnect the suction head from the negative pressure source and to vent such suction head. In the case of high-speed equipment the valve arrangement therefore must be able, with short switching times, to faultlessly establish the requisite negative pressure at the suction head.